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/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 31. July 2014
* $Revision: V1.4.4
*
* Project: CMSIS DSP Library
* Title: arm_bitreversal.c
*
* Description: This file has common tables like Bitreverse, reciprocal etc which are used across different functions
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of ARM LIMITED nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* -------------------------------------------------------------------- */
#include "arm_math.h"
#include "arm_common_tables.h"
/*
* @brief In-place bit reversal function.
* @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
* @param[in] fftSize length of the FFT.
* @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table.
* @param[in] *pBitRevTab points to the bit reversal table.
* @return none.
*/
void arm_bitreversal_f32(
float32_t * pSrc,
uint16_t fftSize,
uint16_t bitRevFactor,
uint16_t * pBitRevTab)
{
uint16_t fftLenBy2, fftLenBy2p1;
uint16_t i, j;
float32_t in;
/* Initializations */
j = 0u;
fftLenBy2 = fftSize >> 1u;
fftLenBy2p1 = (fftSize >> 1u) + 1u;
/* Bit Reversal Implementation */
for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
{
if(i < j)
{
/* pSrc[i] <-> pSrc[j]; */
in = pSrc[2u * i];
pSrc[2u * i] = pSrc[2u * j];
pSrc[2u * j] = in;
/* pSrc[i+1u] <-> pSrc[j+1u] */
in = pSrc[(2u * i) + 1u];
pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
pSrc[(2u * j) + 1u] = in;
/* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
in = pSrc[2u * (i + fftLenBy2p1)];
pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
pSrc[2u * (j + fftLenBy2p1)] = in;
/* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
pSrc[(2u * (j + fftLenBy2p1)) + 1u];
pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
}
/* pSrc[i+1u] <-> pSrc[j+1u] */
in = pSrc[2u * (i + 1u)];
pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
pSrc[2u * (j + fftLenBy2)] = in;
/* pSrc[i+2u] <-> pSrc[j+2u] */
in = pSrc[(2u * (i + 1u)) + 1u];
pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
/* Reading the index for the bit reversal */
j = *pBitRevTab;
/* Updating the bit reversal index depending on the fft length */
pBitRevTab += bitRevFactor;
}
}
/*
* @brief In-place bit reversal function.
* @param[in, out] *pSrc points to the in-place buffer of Q31 data type.
* @param[in] fftLen length of the FFT.
* @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
* @param[in] *pBitRevTab points to bit reversal table.
* @return none.
*/
void arm_bitreversal_q31(
q31_t * pSrc,
uint32_t fftLen,
uint16_t bitRevFactor,
uint16_t * pBitRevTable)
{
uint32_t fftLenBy2, fftLenBy2p1, i, j;
q31_t in;
/* Initializations */
j = 0u;
fftLenBy2 = fftLen / 2u;
fftLenBy2p1 = (fftLen / 2u) + 1u;
/* Bit Reversal Implementation */
for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
{
if(i < j)
{
/* pSrc[i] <-> pSrc[j]; */
in = pSrc[2u * i];
pSrc[2u * i] = pSrc[2u * j];
pSrc[2u * j] = in;
/* pSrc[i+1u] <-> pSrc[j+1u] */
in = pSrc[(2u * i) + 1u];
pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
pSrc[(2u * j) + 1u] = in;
/* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
in = pSrc[2u * (i + fftLenBy2p1)];
pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
pSrc[2u * (j + fftLenBy2p1)] = in;
/* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
pSrc[(2u * (j + fftLenBy2p1)) + 1u];
pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
}
/* pSrc[i+1u] <-> pSrc[j+1u] */
in = pSrc[2u * (i + 1u)];
pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
pSrc[2u * (j + fftLenBy2)] = in;
/* pSrc[i+2u] <-> pSrc[j+2u] */
in = pSrc[(2u * (i + 1u)) + 1u];
pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
/* Reading the index for the bit reversal */
j = *pBitRevTable;
/* Updating the bit reversal index depending on the fft length */
pBitRevTable += bitRevFactor;
}
}
/*
* @brief In-place bit reversal function.
* @param[in, out] *pSrc points to the in-place buffer of Q15 data type.
* @param[in] fftLen length of the FFT.
* @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
* @param[in] *pBitRevTab points to bit reversal table.
* @return none.
*/
void arm_bitreversal_q15(
q15_t * pSrc16,
uint32_t fftLen,
uint16_t bitRevFactor,
uint16_t * pBitRevTab)
{
q31_t *pSrc = (q31_t *) pSrc16;
q31_t in;
uint32_t fftLenBy2, fftLenBy2p1;
uint32_t i, j;
/* Initializations */
j = 0u;
fftLenBy2 = fftLen / 2u;
fftLenBy2p1 = (fftLen / 2u) + 1u;
/* Bit Reversal Implementation */
for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
{
if(i < j)
{
/* pSrc[i] <-> pSrc[j]; */
/* pSrc[i+1u] <-> pSrc[j+1u] */
in = pSrc[i];
pSrc[i] = pSrc[j];
pSrc[j] = in;
/* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */
/* pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */
in = pSrc[i + fftLenBy2p1];
pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1];
pSrc[j + fftLenBy2p1] = in;
}
/* pSrc[i+1u] <-> pSrc[j+fftLenBy2]; */
/* pSrc[i+2] <-> pSrc[j+fftLenBy2+1u] */
in = pSrc[i + 1u];
pSrc[i + 1u] = pSrc[j + fftLenBy2];
pSrc[j + fftLenBy2] = in;
/* Reading the index for the bit reversal */
j = *pBitRevTab;
/* Updating the bit reversal index depending on the fft length */
pBitRevTab += bitRevFactor;
}
}
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